As in 1975, the activities of the F.G. Hall Laboratory for Environmental Research have been directed to the effects of changes in the environment on the physiology and health of man and the study of such changes by health-related scientists and physicians. In so doing, it is hoped to both assist the health and safety of individuals having to live and work in changed environments and also to acquire information which will help in understanding the prognosis and treatment of certain illnesses. Primarily, interest has been directed to pure and applied investigation of the effects of exposure to hyper- and hypobaric environments on cells, tissues, organs and intact organisms. Although not exclusive, these investigations have pursued some seven major aims in diving, hyperbaric and hypobaric oxygen, and respiratory function: (1) Studies of how increased hydrostatic pressure affects cells, tissues, organs, and intact organisms. (2) Study of the mechanisms underlying inert gas narcosis and anesthesia. (3) Studies of the pathophysiology of decompression sickness, its treatment and the means for its prevention. (4) Regulation of respiratory activity. (5) Studies of the metabolic effects of compressed gases, including oxygen. (6) Studies of liquid breathing - a potential method of diving to great depths. (7) Studies of mass and heat transfer.